Chest radiographs and TB
Graham Bothamley
Jean-Paul Zellweger
Plan of session
1.
2.
3.
4.
5.
6.
The typical chest x-ray of TB
Atypical chest x-rays
Extrapulmonary TB on the chest x-ray
Inactive tuberculosis
The normal chest x-ray with C+PTB
Differential diagnoses
What are the typical features of
tuberculosis on a chest x-ray?
Chest x-rays
Study
Under-reading Over-reading
% of positives
% of negatives
5 experts
General
25
27
1.7
Mass radiography
32
1.7
Danish mass radiography
Reader panel (15,000)
10 best radiologists
10 best physicians
32
39
21
26
1.6
1.2
0.5
0.3
Average
32
2
Improvement only if >20,000 films read annually. Nakamura et al. Kekkaku 1970; 45:121
Conclusions from mass x-ray surveys
• Sudden, symptomatic onset as common
as insidious onset
• Disease extent unrelated to duration
(extensive S+PTB within first 3-6 m)
• Cavitation is not a late occurrence – its
frequency is nearly the same at all
temporal stages of the disease
Toman. Case finding and chemotherapy. WHO, Geneva, 1979
Atypical TB
• Lower zone
• No cavitation
• (miliary)
Atypical TB
•
•
•
•
Female
Diabetes
HIV
Elderly
Extrapulmonary TB
•
•
•
•
Mediastinal lymph nodes
Pleural effusions
Paraspinal abscess
Spinal disease
Pleural effusion
Pericardial TB
TB of the spine
Inactive or self-healed tuberculosis
• Primary focus/calcified granuloma
• Coin lesion
• Fibrosis
The normal chest radiograph
with a positive M.tb culture
•
•
•
•
Single isolate or repeated?
Lab contamination – strain typing
CT scan
Treat?
Differential diagnosis
• Non-tuberculous mycobacterial disease
• Sarcoidosis
• Fungal disease
M. xenopi
NTMD
• Background of COPD
• Thicker pleural reaction
M. fortuitum
Tree in bud
Nodules
Bronchiectasis
Mycobacterium spp. Runyon group III
The Quiz
Estimate the probability of the diagnosis of
tuberculosis and indicate whether you think the
person will be sputum smear-positive
• Read the histories and estimate a prior
probability of TB
• Look at the CXRs again – in a different order this
time and again estimate the probability of TB
and whether the sputum smear will be positive
Exercise: 20 CXRs
Estimate the probability of TB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20